This invention relates to multi-functional admixtures for concrete. Recently, the following five functions are coming to be required in order to improve the quality of concrete: (1) It must have superior fluidity that does not deteriorate with time; (2) Hardened materials that are obtained must have a good early strength; (3) The shrinkage rate of hardened materials that are obtained must be low; (4) Hardened materials that are obtained must exhibit a strong resistance against freezing and thawing action; and (5) The carbonation speed of hardened materials that are obtained must be slow. This invention relates to multi-functional admixtures for concrete capable of simultaneously providing all these functions to concrete as well as concrete having all these functions simultaneously.
As shown in Japanese Patent Publications Tokkai 58-74552 and 63-285140 and U.S. Pat. No. 4,962,173, for example, various dispersants containing compounds of polycarboxylic acid have been known as an admixture for concrete capable of providing a superior fluidity that does not deteriorate with time. As shown in U.S. Pat. Nos. 4,547,223 and 5,181,961, on the other hand, various kinds of shrinkage reducing agents have been known as an admixture for concrete for reducing shrinkage of hardened materials obtained from concrete. Moreover, U.S. Pat. Nos. 5,660,626, 5,604,273 and 5,556,460 and Japanese Patent Publications Tokkai 2000-34151, 2001-10853 and 2001-48620, for example, have shown admixtures for concrete capable of not only providing concrete with a superior fluidity that does not deteriorate with time but also reducing the shrinkage of hardened materials obtained from concrete. The problem still remains with these prior art admixtures for concrete that, even if they are used singly or in combination, they cannot satisfy all of the required functions at the same time.